1. Field of the Invention
The present invention pertains to techniques for establishing electrical connections. More particularly, the present invention relates to apparatus and methods for coupling conductors carrying electronic signals, and finds particular application in the connection of cable segments mounted in pipe members wherein the individual cable segments are coupled at the pipe joints.
2. Description of the Background
In the practice of drilling wells and in other well working operations various procedures involve the transmission of information from within the well to instrumentation at the surface to convey data reflecting downhole conditions. Such cases include measurement while drilling procedures wherein underground formation characteristics are logged while the well is being drilled. Electronic signals are also transmitted from the surface to downhole apparatus to initiate logging procedures or explosives, for example.
Various methods have been employed or suggested for communicating electronic and other signals between downhole locations and the surface. Mud pulsing may be utilized to transmit data to the surface by means of pressure surges generated in the drilling mud within a drill string by operation of a downhole valve according to the data gathered and to be transmitted. Electromagnetic wave propogation may also be utilized to transmit data to the surface. Such wave techniques are generally limited to the rates at which data bits may be transmitted.
Techniques for providing electrical conductors in pipe strings are known. Such techniques include incorporating conductors within the individual pipe members, or mounting cable segments within the pipe members. The individual cable segments are interconnected at the pipe joints of a pipe string. Ohmic contacts between the cable segments, or jumper cables, may be utilized to connect the cable segments into a continuous transmission path. Cables and other conductors provided in conjunction with a pipe string may be utilized to transmit signals from the surface to control various downhole functions in addition to transmitting information to the surface from below.
While cable and other tubing-carried conductors permit relatively high rates of data transmission between the surface and downhole locations, drill pipe especially modified to accomodate or include such conductors is generally expensive, and may interfere with normal drilling operations. Special joint greases are also required to reduce electrical leakage, further interfering with rig floor operations.